The present invention relates to a method for operating a pedestrian protection system for reducing the severity of an accident in frontal collisions with pedestrians in a motor vehicle, as well as to a motor vehicle having a pedestrian protection system.
Various measurements have recently been proposed for protecting pedestrians in a frontal accident with motor vehicles. These measurements are realized with safety systems, in particular passive measures. Pedestrian protection systems are known wherein one or several collision sensors (contact sensors serving as detection devices are installed in the front region (front end) of the motor vehicle. These collision sensors typically detect an impact of a pedestrian or of another object. A corresponding algorithm evaluates different features of the measurement data (sensor signals) and decides based on a trigger condition, which may also include several nested criteria, whether a safety system should be triggered, in particular as a passive measure.
The following discussion of related art is provided to assist the reader in understanding the advantages of the invention, and is not to be construed as an admission that this related art is prior art to this invention.
Conventional sensors are frequently unable to supply a reliable classification with respect to a real pedestrian, and corresponding algorithms are also designed for triggering a replacement impactor, so that the aforementioned features and/or safety systems can also be triggered by mistake when the impact of an object at the front end of the motor vehicle is similar to that of a pedestrian or of a replacement impactor. Optical detection devices, in particular optical sensors, are typically also not able to identify with sufficient reliability the class “pedestrian”, potentially causing false triggering.
Although false triggering is still acceptable with reversible measures, i.e. with safety systems having actuators constructed to also restore the triggered safety system, because they can be readily restored by the driver himself or by a corresponding repair shop, for example in the case of a returnable crash-active engine hood. However, a driver will probably complain about an erroneously triggered safety system, in particular an exterior airbag. In addition, the view of the driver is disadvantageously obscured when an exterior airbag on the windshield is erroneously triggered.
For example, when evaluating optical measurement data, false triggering may be caused by airborne plastic bags, birds, branches and the like, wherein with a contact sensor or collision sensor in the front end false triggering may be caused by small animals, wildlife, airborne plastic bags, posts, guard rails, balls and the like. It has therefore been proposed to use two independent sensors, each confirming an event to prevent false triggering. For example, a variable of the first object characterizing a mass and/or a hardness could be evaluated based on the applied force and the relative speed, with the object being recognized as a certain object type when the estimated variable characterizing the mass and/or the hardness is within a predetermined range. However, this requires a very complex evaluation algorithm which in itself is susceptive to errors and which must link a large number of features of the measurement data in a complex manner, in particular also with respect to criteria of the trigger condition.
It would therefore be desirable and advantageous to address this problem and to obviate other prior art shortcomings by providing a method for operating a pedestrian protection system, wherein an additional plausibility criterion within the trigger condition can be realized in a simple manner.